This invention relates to an optical coupling apparatus including a semiconductor light emitting device and an optical fiber that are optically connected to each other. More particularly, the invention relates to a single lens optical coupling apparatus that attains optical coupling by use of a single lens.
A known optical coupling apparatus allows an outgoing beam from a semiconductor laser to be incident into an end face of an optical fiber through a lens, and optical coupling is attained between the semiconductor laser and the optical fiber through the single lens, as described in JP-A-05-150146. This reference discloses a construction in which the semiconductor laser, the lens and a light reception device are mounted onto a substrate having thick portions on both sides thereof that are parallel to an optical axis to suppress the change of optical coupling in the optical axis direction and to reduce an optical axis error.
Another reference, JP-A-11-330564, describes optical coupling between an optical semiconductor device and an optical fiber by use of a single lens. The optical semiconductor device and the lens are mounted onto a block. The block is arranged on a heat sink and is encompassed by a package. An optical fiber is inserted and fixed into a cylindrical optical fiber fixing portion disposed on a side surface of the package. Fixing members capable of deformation are interconnected to a package main body to prevent an optical axis error of the package resulting from thermal expansion of the heat sink when the heat sink is screw-fixed to mount an optical communication appliance. Still another reference, JP-A-2001-284699, discloses a construction in which two lenses are used to optically couple a semiconductor laser and an optical fiber, and the semiconductor laser and a first lens are mounted onto a base and are disposed on a bottom plate of a package through a Peltier device. A fitting cylinder is so fitted as to protrude from inside and outside of the package, and a second lens and the optical fiber are disposed inside the cylinder and at an end portion, respectively.